Heat exchanger

ABSTRACT

An evaporator includes two header tanks and a plurality of heat exchange tubes disposed therebetween. The interior of a refrigerant inlet header section of the first header tank is divided into two spaces by a first flow diverging plate. The heat-exchange-tube-side space of the refrigerant inlet header section is divided into a plurality of sections by a first partition plate. Flow diverging openings are provided in portions of the first flow diverging plate facing the sections. The interiors of first and second intermediate header sections of the second header tank are each divided into sections, equal in number to those of the refrigerant inlet header section. The heat exchange tubes communicating with the sections of the refrigerant inlet header section communicate with the sections of the first intermediate header section, and the sections of the first intermediate header section communicate with the corresponding sections of the second intermediate header section.

BACKGROUND OF THE INVENTION

The present invention relates to a heat exchanger which is suitably usedas an evaporator of a car air conditioner, which is a refrigerationcycle to be mounted on an automobile, for example.

The present applicant has proposed a heat exchanger which is used as anevaporator of a car air conditioner and which satisfies the requirementsfor reduction in size and weight and higher performance (refer toJapanese Patent Application Laid-Open (kokai) No. 2003-75024). The heatexchanger includes first and second header tanks disposed apart fromeach other, and a heat exchange core section provided between the headertanks. In the first header tank, a refrigerant inlet header sectionhaving a refrigerant inlet and a refrigerant outlet header sectionhaving a refrigerant outlet are juxtaposed in an air flow direction. Inthe second header tank, a first intermediate header section and a secondintermediate header section are juxtaposed in the air flow direction.The first intermediate header section and the second intermediate headersection communicate with each other. The heat exchange core sectionincludes a first heat exchange tube row, a second heat exchange tuberow, and corrugate fins. The first heat exchange tube row includes aplurality of heat exchange tubes which are separated from one another inthe longitudinal direction of the header tanks and whose opposite endportions are connected to the refrigerant inlet header section and thefirst intermediate header section, respectively. The second heatexchange tube row includes a plurality of heat exchange tubes which areseparated from one another in the longitudinal direction of the headertanks and whose opposite end portions are connected to the refrigerantoutlet header section and the second intermediate header section,respectively. The corrugate fins are disposed in air-passing clearances,each formed between heat exchange tubes adjacent to each other withrespect to the longitudinal direction of the header tanks, and on theouter sides of the heat exchange tubes located at the opposite ends, insuch a manner that the corrugate fins are shared by the heat exchangetubes of the first heat exchange tube row and those of the second heatexchange tube row. The corrugate fins are brazed to the heat exchangetubes of the first and second heat exchange tube rows.

In the heat exchanger disclosed in Japanese Patent Application Laid-OpenNo. 2003-75024, the refrigerant inlet of the refrigerant inlet headersection and the refrigerant outlet of the refrigerant outlet headersection are formed at the same end portion of the first header tank orin a longitudinal center portion of the first header tank at positionsclose to each other with respect to the longitudinal direction.

However, through various studies, the present inventor has found that,although the heat exchanger disclosed in Japanese Patent ApplicationLaid-Open No. 2003-75024 usually has a sufficiently high heat exchangeperformance, when a further improvement of heat exchange performance isrequired, in some cases the heat exchanger fails to satisfy thatrequirement. That is, in the case where the refrigerant inlet of therefrigerant inlet header section and the refrigerant outlet of therefrigerant outlet header section are formed at the same end portion ofthe first header tank or in a longitudinal center portion of the firstheader tank at positions close to each other with respect to thelongitudinal direction, when refrigerant flows from the refrigerantinlet to the refrigerant outlet, a large amount of the refrigerant mayflow through heat exchange tubes of the first and second heat exchangetube rows, the heat exchange tubes being located close to therefrigerant inlet and the refrigerant outlet, and the amount ofrefrigerant flowing through the remaining exchange tubes may decrease,whereby the refrigerant flowing amounts of all the heat exchange tubesbecome non-uniform. As a result, the temperature of air having passedthrough the heat exchange core section becomes non-uniform; i.e., varieswith location. Thus, the effect of further improving the heat exchangeperformance of the heat exchanger cannot be attained sufficiently.

In order to solve such a problem, the present applicant has proposed animprovement on the heat exchanger disclosed in Japanese PatentApplication Laid-Open No. 2003-75024 (refer to, Japanese PatentApplication Laid-Open (kokai) No. 2006-170598). In the improvement, theinterior of the refrigerant inlet header section of the first headertank is partitioned into two spaces in the longitudinal direction of theheat exchange tubes by a first diverging flow control wall having aplurality of refrigerant passage holes; the interior of the refrigerantoutlet header section of the first header tank is partitioned into twospaces in the longitudinal direction of the heat exchange tubes by asecond diverging flow control wall having a plurality of refrigerantpassage holes; the interior of the second intermediate header section ofthe second header tank is partitioned into two spaces in thelongitudinal direction of the heat exchange tubes by a third divergingflow control wall having a plurality of refrigerant passage holes; andthe interior of the first intermediate header section of the secondheader tank and the outer section of the second intermediate headersection with respect to the longitudinal direction of the heat exchangetubes are connected together at one end portion of the second headertank.

According to the heat exchanger disclosed in Japanese Patent ApplicationLaid-Open No. 2006-170598, diverging flow into all the heat exchangetubes of the two heat exchange tube row occurs uniformly, and therefrigerant flowing amounts of all the heat exchange tubes are rendereduniform, whereby heat exchange performance is improved further. However,in the case of the heat exchanger disclosed in Japanese PatentApplication Laid-Open No. 2006-170598, a large flow passage resistanceacts on refrigerant when the refrigerant passes through the refrigerantpassage holes of the first through third diverging flow control walls,whereby the heat exchange performance improving effect may be impeded.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the above problem and toprovide a heat exchanger which has an improved heat exchangeperformance.

To fulfill the above object, the present invention comprises thefollowing modes.

1) A heat exchanger comprising first and second header tanks disposedapart from each other; and a plurality of heat exchange tubes which aredisposed between the header tanks and whose opposite end portions areconnected to the corresponding header tanks, wherein the first headertank includes a refrigerant inlet header section and a refrigerantoutlet header section juxtaposed in an air flow direction, the secondheader tank includes a first intermediate header section and a secondintermediate header section juxtaposed in the air flow direction, andthe heat exchange tubes establish communication between the refrigerantinlet header section and the first intermediate header section andcommunication between the refrigerant outlet header section and thesecond intermediate header section, wherein

-   -   a portion of the interior of the refrigerant inlet header        section, the portion communicating with the heat exchange tubes,        is divided into a plurality of sections in a longitudinal        direction of the header tanks;    -   flow diverging means is provided in the refrigerant inlet header        section so as to cause refrigerant having flowed into the        refrigerant inlet header section to diverge into the sections;    -   each of the interiors of the first intermediate header section        and the second intermediate header section is divided into        sections in the longitudinal direction of the header tanks, the        number of the sections being equal to the number of the sections        of the refrigerant inlet header section;    -   the heat exchange tubes communicating with the sections of the        refrigerant inlet header section communicate with the        corresponding sections of the first intermediate header section;        and    -   the sections of the first intermediate header section        communicate with the corresponding sections of the second        intermediate header section.

2) A heat exchanger according to par. 1), wherein the interior of therefrigerant inlet header section is divided into two spaces in thelongitudinal direction of the heat exchange tubes by an inlet headersection flow diverging member; a first space of the refrigerant inletheader section located on a side toward the heat exchange tubes servesas the portion communicating with the heat exchange tubes; the firstspace is divided into a plurality of sections in the longitudinaldirection of the header tanks by an inlet header section partitionmember; refrigerant flows into a second space of the refrigerant inletheader section located on a side opposite the heat exchange tubes; andflow diverging means composed of a flow diverging opening is provided ineach of portions of the inlet header section flow diverging membercorresponding to the sections of the first space so as to cause therefrigerant having flowed into the second space of the refrigerant inletheader section to diverge into the corresponding spaces.

3) A heat exchanger according to par. 1), wherein each of the sectionsof the second intermediate header section of the second header tank isdivided into two spaces in the longitudinal direction of the heatexchange tubes by a second intermediate header section flow divergingmember, and communication is established between the two spaces of eachsection.

4) A heat exchanger according to par. 1), wherein the interior of therefrigerant outlet header section of the first header tank is dividedinto two spaces in the longitudinal direction of the heat exchange tubesby an outlet header section flow diverging member; a space of therefrigerant outlet header section located on a side toward the heatexchange tubes serves a portion communicating with the heat exchangetubes; the space located on the side toward the heat exchange tubes isdivided into a plurality of sections in the longitudinal direction ofthe header tanks by an outlet header section partition member, thenumber of sections being equal to the number of sections of therefrigerant inlet header section; and the sections of the space locatedon the side toward the heat exchange tubes communicate with a space ofthe refrigerant outlet header section located on a side opposite theheat exchange tubes.

5) A heat exchanger according to par. 1), wherein each of the number ofthe sections of the refrigerant inlet header section of the first headertank, the number of the sections of the first intermediate headersection of the second header tank, and the number of the sections of thesecond intermediate header section of the second header tank is two; thesections of the first intermediate header section and the secondintermediate header section located on one side with respect to thelongitudinal direction of the header tanks communicate with each othervia a communication portion provided at one end of the second headertank; and the sections of the first intermediate header section and thesecond intermediate header section located on the other side withrespect to the longitudinal direction of the header tanks communicatewith each other via a communication portion provided at the other end ofthe second header tank.

6) A heat exchanger according to par. 1), wherein the interior of thesecond header tank is divided into two spaces in the air flow directionby a partition member so that the first intermediate header section andthe second intermediate header section are formed; and refrigerantpassage holes are formed in the partition member so as to establishcommunication between the first intermediate header section and thesecond intermediate header section.

According to the heat exchanger of par. 1), a portion of the interior ofthe refrigerant inlet header section, the portion communicating with theheat exchange tubes, is divided into a plurality of sections in thelongitudinal direction of the header tanks; flow diverging means isprovided in the refrigerant inlet header section so as to causerefrigerant having flowed into the refrigerant inlet header section todiverge into the sections; each of the interiors of the firstintermediate header section and a second intermediate header section isdivided into sections in the longitudinal direction of the header tanks,the number of the sections being equal to the number of the sections ofthe refrigerant inlet header section; the heat exchange tubescommunicating with the sections of the refrigerant inlet header sectioncommunicate with the corresponding sections of the first intermediateheader section; and the sections of the first intermediate headersection of the second header tank communicate with the correspondingsections of the second intermediate header section of the second headertank. Therefore, refrigerant caused by the flow diverging means todiverge into the sections of the refrigerant inlet header section flowsthrough the heat exchange tubes into the corresponding sections of thefirst intermediate header section, enters the corresponding sections ofthe second intermediate header section, flows through the heat exchangetubes into the refrigerant outlet header section, and flows out from therefrigerant outlet. Therefore, the amount of refrigerant flowing fromeach section of the second intermediate header section to therefrigerant outlet header section is always equal to the amount ofrefrigerant flowing from each section of the refrigerant inlet headersection to the corresponding section of the first intermediate headersection. As a result, the diverging flow into all the heat exchangetubes is performed uniformly, and the refrigerant flow amounts of allthe heat exchange tubes are made uniform, whereby heat exchangeperformance is improved further. Moreover, unlike the heat exchangerdisclosed in Japanese Patent Application Laid-Open No. 2006-170598, theheat exchanger of par. 1) does not require first through third divergingflow control walls. Therefore, the channel resistance which acts onrefrigerant upon passage through the heat exchanger can be reduced,whereby an excellent effect of improving the heat exchange performanceis attained.

Further, according to an evaporator to which the heat exchanger ofpar. 1) is applied, even when air passing through the evaporatorproduces a relatively large difference in flow speed between one end andthe other end with respect to the longitudinal direction of the headertanks, a change in the temperature of air having passed through theevaporator with respect to the longitudinal direction of the headertanks can be reduced. When air passing through the evaporator disclosedin Japanese Patent Application Laid-Open No. 2003-75024 produces arelatively large difference in flow speed between one end and the otherend with respect to the longitudinal direction of the header tanks, thefollowing phenomenon occurs. That is, on the side where the air flowspeed is large, refrigerant is likely to vaporize, so that a largeamount of vapor-phase refrigerant flows through the heat exchange tubesand receives a large resistance. In contrast, on the side where the airflow speed is small, a large amount of liquid-phase refrigerant flowsthrough the heat exchange tube. Therefore, the temperature of air havingpassed through the evaporator also becomes non-uniform with respect tothe longitudinal direction of the header tanks. However, in the case ofthe evaporator to which the heat exchanger of par. 1) is applied, evenwhen air passing through the evaporator produces a relatively largedifference in flow speed between one end and the other end with respectto the longitudinal direction of the header tanks, air passing througheach of areas corresponding to the extents of the respective sections ofthe refrigerant inlet header section, the first intermediate headersection, and the second intermediate header section does not produce alarge difference in flow speed between one end and the other end of thecorresponding area with respect to the longitudinal direction of theheader tanks. Accordingly, the amounts of refrigerant flowing throughthe heat exchange tubes located in the area corresponding to the extentof each section is rendered uniform, whereby a change in the temperatureof air having passed through the evaporator with respect to thelongitudinal direction of the header tanks can be reduced.

Moreover, according to the evaporator to which the heat exchanger ofpar. 1) is applied, even when the flow speed of air passing through theevaporator changes relatively greatly depending on the position withrespect to the longitudinal direction of the header tanks; that is, theflow speed of air passing through each of areas corresponding to theextents of the respective sections of the refrigerant inlet headersection, the first intermediate header section, and the secondintermediate header section differs relatively greatly among the areascorresponding to the extents of the respective sections, the flow ofrefrigerant flowing through the heat exchange tubes which communicatewith the sections corresponding to a region where the air-flow speed islow becomes unlikely to receive the influence of the flow of refrigerantflowing through the heat exchange tubes which communicate with thesections corresponding to a region where the air-flow speed is high.Thus, in each of regions corresponding to the heat exchange tubes whichcommunicate with the respective sections, the temperature of air havingpassed through the evaporator is made uniform in the longitudinaldirection of the respective sections. Accordingly, a change in thetemperature of air having passed through the evaporator with respect tothe longitudinal direction of the header tanks can be reduced.

According to the heat exchanger of par. 2), the refrigerant flowingamounts of all the heat exchange tubes can be rendered more uniform, ascompared with the heat exchanger of par. 1).

According to the heat exchanger of par. 3), the refrigerant flowingamounts of all the heat exchange tubes can be rendered more uniform, ascompared with the heat exchanger of par. 1).

According to the heat exchanger of par. 4), the refrigerant flowingamounts of all the heat exchange tubes can be rendered more uniform, ascompared with the heat exchanger of par. 1).

According to the heat exchanger of par. 5), through adjustment of thesectional areas of flow passages of the communication portions, theamount of refrigerant flowing through one section of the refrigerantinlet header section of the first header tank, one section of the firstintermediate header section of the second header tank, and one sectionof the second intermediate header section of the second header tank canbe made equal to the amount of refrigerant flowing through the othersection of the refrigerant inlet header section of the first headertank, the other section of the first intermediate header section of thesecond header tank, and the other section of the second intermediateheader section of the second header tank. Accordingly, the divergingflow into all the heat exchange tubes is performed uniformly, and therefrigerant flow amounts of all the heat exchange tubes are madeuniform, whereby heat exchange performance is improved further.

According to the heat exchanger of par. 6), since a flow path throughwhich refrigerant flows can be shortened, the flow passage resistancecan be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut-away perspective view showing the overallstructure of a first embodiment of an evaporator to which a heatexchanger according to the present invention is applied;

FIG. 2 a is a partially-omitted cross sectional view taken along lineA-A of FIG. 1, and FIG. 2 b is a partially-omitted cross sectional viewtaken along line B-B of FIG. 1;

FIG. 3 a is a view corresponding to FIG. 2 a and showing the overallstructure of a second embodiment of the evaporator to which the heatexchanger according to the present invention is applied, and FIG. 3 b isa view corresponding to FIG. 2 b and showing the overall structure ofthe second embodiment of the evaporator to which the heat exchangeraccording to the present invention is applied;

FIG. 4 a is a view corresponding to FIG. 2 a and showing the overallstructure of a third embodiment of the evaporator to which the heatexchanger according to the present invention is applied, and FIG. 4 b isa view corresponding to FIG. 2 b and showing the overall structure ofthe third embodiment of the evaporator to which the heat exchangeraccording to the present invention is applied;

FIG. 5 a is a view corresponding to FIG. 2 a and showing the overallstructure of a fourth embodiment of the evaporator to which the heatexchanger according to the present invention is applied, and FIG. 5 b isa view corresponding to FIG. 2 b and showing the overall structure ofthe fourth embodiment of the evaporator to which the heat exchangeraccording to the present invention is applied; and

FIG. 6 is a view corresponding to FIG. 2 a and showing a modification ofthe inlet header section of the first header tank.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will next be describedwith reference to the drawings. The embodiments are implemented byapplying a heat exchanger according to the present invention to anevaporator of a car air conditioner using a chlorofluorocarbon-basedrefrigerant.

Notably, in the following description, the term “aluminum” encompassesaluminum alloys in addition to pure aluminum.

In the following description, the downstream side (a directionrepresented by arrow X in FIG. 1) of an air flow through air-passingclearances between adjacent heat exchange tubes will be referred to asthe “front,” and the opposite side as the “rear,” and the upper, lower,left-hand, and right-hand sides of the drawings will be referred to as“upper,” “lower,” “left,” and “right,” respectively.

Further, identical portions and identical members are denoted by thesame reference numerals throughout the drawings, and redundantdescriptions are eliminated.

First Embodiment

The present embodiment is shown in FIGS. 1 and 2, which show the overallconfiguration of an evaporator.

As shown in FIG. 1, an evaporator 1 includes a first header tank 2 and asecond header tank 3, which are formed of aluminum and are disposedapart from each other in the vertical direction, and a heat exchangecore section 4 provided between the first and second header tanks 2 and3.

The first header tank 2 includes a refrigerant inlet header section 5located on the front side (downstream side with respect to the air flowdirection), and a refrigerant outlet header section 6 located on therear side (upstream side with respect to the air flow direction) andintegrated with the refrigerant inlet header section 5. A refrigerantinlet 7 is provided in a right end portion of the refrigerant inletheader section 5, and a refrigerant outlet 8 is provided in a right endportion of the refrigerant outlet header section 6. The second headertank 3 includes a first intermediate header section 9 located on thefront side, and a second intermediate header section 11 located on therear side and integrated with the first intermediate header section 9.In the present embodiment, the refrigerant inlet header section 5 andthe refrigerant outlet header section 6 are formed by partitioning theinterior of the first header tank 2 by means of a vertical partitionwall 12, and the first intermediate header section 9 and the secondintermediate header section 11 are formed by partitioning the interiorof the second header tank 3 by means of a vertical partition wall 13.

The heat exchange core section 4 is configured as follows. Heat exchangetube rows 15 and 16 are arranged in a plurality of; herein, two, rows inthe front-rear direction. Each of the heat exchange tube rows 15 and 16is composed of a plurality of flat heat exchange tubes 14, which aremade of aluminum, are arranged at predetermined intervals in theleft-right direction, and extend in the vertical direction. Corrugatedfins 17 made of aluminum are disposed within corresponding air-passingclearances between the adjacent heat exchange tubes 14 of the heatexchange tube rows 15 and 16 and externally of the left-end andright-end heat exchange tubes 14 of the heat exchange tube rows 15 and16 in such a manner that the corrugated fins 17 face both the exchangetubes 14 of the front heat exchange tube rows 15 and those of the rearheat exchange tube row 16. The corrugated fins 17 are brazed to theexchange tubes 14 of the heat exchange tube rows 15 and 16. Side plates18 made of aluminum are disposed externally of the left-end andright-end corrugated fins 17 and are brazed to the correspondingcorrugated fins 17.

The heat exchange tubes 14 of the front heat exchange tube row 15 aredisposed between the refrigerant inlet header section 5 of the firstheader tank 2 and the first intermediate header section 9 of the secondheader tank 3; and upper and lower end portions of the heat exchangetubes 14 of the front heat exchange tube row 15 are connected to therefrigerant inlet header section 5 and the first intermediate headersection 9, respectively. The heat exchange tubes 14 of the rear heatexchange tube row 16 are disposed between the refrigerant outlet headersection 6 of the first header tank 2 and the second intermediate headersection 11 of the second header tank 3; and upper and lower end portionsof the heat exchange tubes 14 of the rear heat exchange tube row 16 areconnected to the refrigerant outlet header section 6 and the secondintermediate header section 11, respectively.

As shown in FIGS. 2 a and 2 b, the interior of the refrigerant inletheader section 5 of the first header tank 2 is divided into two spaces 5a and 5 b in the vertical direction by a first horizontal flow divergingplate 19 (an inlet header section flow diverging member). Notably, therefrigerant inlet 7 communicates with the upper space 5 a. The lowerspace 5 b of the refrigerant inlet header section 5 (a space on the sidetoward the heat exchange tubes 14), which communicates with the heatexchange tubes 14, is divided into a plurality of (in the presentembodiment, two) sections 22 and 23 in the left-right direction (thelongitudinal direction of the first header tank 2) by a first verticalpartition plate 21 (an inlet header section partition member). Flowdiverging means, which is constituted by a flow diverging opening 24assuming the form of a through hole, is provided at the left ends (thedownstream ends with respect to the refrigerant flow direction) ofportions of the first flow diverging plate 19, the portions facing thesections 22 and 23, so as to cause the refrigerant having flowed intothe upper space 5 a of the refrigerant inlet header section 5 to divergeinto the sections 22 and 23.

The interiors of the first intermediate header section 9 and the secondintermediate header section 11 of the second header tank 3 arerespectively divided into sections 27 and 28 and sections 29 and 31,which are the same in number as the sections 22 and 23 of therefrigerant inlet header section 5, in the left-right direction (thelongitudinal direction of the first header tank 2) by second and thirdvertical partition plates 25 and 26 (a first intermediate header sectionpartition member and a second intermediate header section partitionmember), respectively. The length (as measured in the left-rightdirection) of the sections 27, 28, 29, and 31 within the firstintermediate header section 9 and the second intermediate header section11 is equal to the length (as measured in the left-right direction) ofthe sections 22 and 23 within the lower space 5 b of the refrigerantinlet header section 5. The heat exchange tubes 14 which communicatewith the sections 22 and 23 of the lower space 5 b of the refrigerantinlet header section 5 communicate with the sections 27 and 28 withinthe first intermediate header section 9. The right-side sections 27 and29 (located on one side with respect to the longitudinal direction ofthe header tanks) of the first intermediate header section 9 and thesecond intermediate header section 11 communicate with each other via acommunication portion 32 provided at the right end of the second headertank 3; and the left-side sections 28 and 31 (located on the other sidewith respect to the longitudinal direction of the header tanks) of thefirst intermediate header section 9 and the second intermediate headersection 11 communicate with each other via a communication portion 33provided at the left end of the second header tank 3.

The heat exchange tubes 14 which constitute the front heat exchange tuberow 15 are divided into a first heat exchange tube group 15A whichcommunicates with the right-side section 22 of the refrigerant inletheader section 5 of the first header tank 2 and the right-side section27 of the first intermediate header section 9 of the second header tank3, and a second heat exchange tube group 15B which communicates with theleft-side section 23 of the refrigerant inlet header section 5 of thefirst header tank 2 and the left-side section 28 of the firstintermediate header section 9 of the second header tank 3. Further, theheat exchange tubes 14 which constitute the rear heat exchange tube row16 are divided into a third heat exchange tube group 16A which iscomposed of the heat exchange tubes 14 which are disposed on the rearside of the heat exchange tubes 14 of the first heat exchange tube group15A and which communicate with the right-side section 29 of the secondintermediate header section 11 of the second header tank 3, and a fourthheat exchange tube group 16B which is composed of the heat exchangetubes 14 which are disposed on the rear side of the heat exchange tubes14 of the second heat exchange tube group 15B and which communicate withthe left-side section 31 of the second intermediate header section 11 ofthe second header tank 3.

The above-described evaporator 1, together with a compressor and acondenser serving as a refrigerant cooler, constitutes a refrigerationcycle which uses a chlorofluorocarbon-based refrigerant. Thisrefrigeration cycle is installed in a vehicle, such as an automobile, asa car air conditioner. A two-phase refrigerant of vapor-liquid phasehaving passed through the compressor, the condenser, and an expansionvalve flows through the refrigerant inlet 7 and enters the upper space 5a of the refrigerant inlet header section 5 of the first header tank 2.In the upper space 5 a of the refrigerant inlet header section 5, therefrigerant flows leftward, and enters the sections 22 and 23 of thelower space 5 b via the diverging openings 24.

In the spaces 22 and 23 of the lower space 5 b of the refrigerant inletheader section 5, the refrigerant diverges into the heat exchange tubes14 of the heat exchange tube groups 15A and 15B of the front heatexchange tube row 15. The refrigerant then flows downward within theheat exchange tubes 14 and enters the sections 27 and 28 of the firstintermediate header section 9 of the second header tank 3. Therefrigerant having entered the right-side section 27 of the firstintermediate header section 9 flows rightward and enters the right-sidesection 29 of the second intermediate header section 11 via thecommunication portion 32 at the right end. Meanwhile, the refrigeranthaving entered the left-side section 28 of the first intermediate headersection 9 flows leftward and enters the left-side section 31 of thesecond intermediate header section 11 via the communication portion 33at the left end.

The refrigerant having entered the sections 29 and 31 of the secondintermediate header section 11 diverges and flows into the heat exchangetubes 14 of the heat exchange tube groups 16A and 16B of the rear heatexchange tube row 16. The refrigerant then flows upward within the heatexchange tubes 14 and enters the refrigerant outlet header section 6 ofthe first header tank 2. The refrigerant having entered the refrigerantoutlet header section 6 flows rightward and flows to the outside via therefrigerant outlet 8.

While flowing through the heat exchange tubes 14 of the front heatexchange tube row 15 and the heat exchange tubes 14 of the rear heatexchange tube row 16, the refrigerant is subjected to heat exchange withair flowing through the air-passing clearances of the heat exchange coresection 4 (see arrow X of FIG. 1). Then, the refrigerant flows out fromthe evaporator in a vapor phase.

At that time, the amount of refrigerant flowing from each of thesections 29 and 31 of the second intermediate header section 11 to therefrigerant outlet header section 6 is always equal to the amount ofrefrigerant flowing from each of the sections 22 and 23 of therefrigerant inlet header section 5 to the corresponding section 27 or 28of the first intermediate header section 9. That is, the total amount ofrefrigerant flowing through the heat exchange tubes 14 which constitutethe third heat exchange tube group 16A of the rear heat exchange tuberow 16 is equal to the total amount of refrigerant flowing through theheat exchange tubes 14 which constitute the first heat exchange tubegroup 15A of the front heat exchange tube row 15; and the total amountof refrigerant flowing through the heat exchange tubes 14 whichconstitute the fourth heat exchange tube group 16B of the rear heatexchange tube row 16 is equal to the total amount of refrigerant flowingthrough the heat exchange tubes 14 which constitute the second heatexchange tube group 15B of the front heat exchange tube row 15. As aresult, the diverging flow into all the heat exchange tubes 14 isperformed uniformly, and the refrigerant flow amounts of all the heatexchange tubes 14 are rendered uniform, whereby heat exchangeperformance is improved.

Further, even when air passing through the evaporator 1 produces arelatively large difference in flow speed between one end and the otherend with respect to the left-right direction, air passing through eachof areas corresponding to the extents (with respect to the left-rightdirection) of the respective sections 22, 23, 27, 28, 29, and 31 of therefrigerant inlet header section 5, the first intermediate headersection 9, and the second intermediate header section 11 does notproduce a large difference in flow speed between one end and the otherend of each of the areas corresponding to the extents of the respectivesections 22, 23, 27, 28, 29, and 31. That is, air passing through theair-passing clearances between the adjacent heat exchange tubes 14 ofthe first heat exchange tube group 15A of the front heat exchange tuberow 15 and the third heat exchange tube group 16A of the rear heatexchange tube row 16 and air passing through the air-passing clearancesbetween the adjacent heat exchange tubes 14 of the second heat exchangetube group 15B of the front heat exchange tube row 15 and the fourthheat exchange tube group 16B of the rear heat exchange tube row 16 donot produce a large difference in flow speed between one end and theother end of each of the areas corresponding to the extents of therespective sections 22, 23, 27, 28, 29, and 31. Accordingly, all theamounts of refrigerant flowing through the heat exchange tubes 14located in the areas corresponding the extents of the respectivesections 22, 23, 27, 28, 29, and 31; that is, all the flow amounts ofrefrigerant flowing through the heat exchange tubes 14 which constitutethe first heat exchange tube group 15A of the front heat exchange tuberow 15, all the flow amounts of refrigerant flowing through the heatexchange tubes 14 which constitute the third heat exchange tube group16A of the rear heat exchange tube row 16, all the flow amounts ofrefrigerant flowing through the heat exchange tubes 14 which constitutethe second heat exchange tube group 15B of the front heat exchange tuberow 15, and all the flow amounts of refrigerant flowing through the heatexchange tubes 14 which constitute the fourth heat exchange tube group16B of the rear heat exchange tube row 16, are respectively madeuniform, whereby a change in the temperature of air having passedthrough the evaporator 1 with respect to the left-right direction can bereduced.

Moreover, in some cases, the flow speed of air passing through the areascorresponding to the extents of the respective sections 22, 23, 27, 28,29, and 31 of the refrigerant inlet header section 5, the firstintermediate header section 9, and the second intermediate headersection 11 differ relatively greatly among the areas corresponding tothe extents of the respective sections 22, 23, 27, 28, 29, and 31; thatis, the flow speed of air passing through the air-passing clearancesbetween the adjacent heat exchange tubes 14 of the first heat exchangetube group 15A of the front heat exchange tube row 15 and the third heatexchange tube group 16A of the rear heat exchange tube row 16 differsrelatively greatly from the flow speed of air passing through theair-passing clearances between the adjacent heat exchange tubes 14 ofthe second heat exchange tube group 15B of the front heat exchange tuberow 15 and the fourth heat exchange tube group 16B of the rear heatexchange tube row 16. Even in such a case, the flow of refrigerantflowing through the heat exchange tubes 14 of the heat exchange tubegroups which communicate with the sections corresponding to a regionwhere the air-flow speed is low becomes unlikely to receive theinfluence of the flow of refrigerant flowing through the heat exchangetubes 14 of the heat exchange tube groups which communicate with thesections corresponding to a region where the air-flow speed is high.Thus, in each of regions corresponding to the heat exchange tubes 14 ofthe heat exchange tube groups which communicate with the respectivesections 22, 23, 27, 28, 29, and 31, the temperature of air havingpassed through the evaporator 1 is made uniform in the longitudinaldirection of the respective sections 22, 23, 27, 28, 29, and 31.Accordingly, a change in the temperature of air having passed throughthe evaporator 1 with respect to the left-right direction can bereduced.

Second Embodiment

The present embodiment is shown in FIGS. 3 a and 3 b, which show theentire structure of an evaporator.

In the case of the evaporator 40 shown in FIGS. 3 a and 3 b, theinterior of the refrigerant outlet header section 6 of the first headertank 2 is divided into two spaces 6 a and 6 b in the vertical direction(the longitudinal direction of the heat exchange tubes 14) by a secondhorizontal flow diverging plate 41 (an outlet header section flowdiverging member). Notably, the refrigerant outlet 8 communicates withthe upper space 6 a. The lower space 6 b of the refrigerant outletheader section 6 (a space on the side toward the heat exchange tubes14), which communicates with the heat exchange tubes 14, is divided intosections 43 and 44 in the left-right direction (the longitudinaldirection of the first header tank 2) by a second vertical partitionplate 42 (an outlet header section partition member). The sections 43and 44 are equal in number to the sections 22 and 23 of the refrigerantinlet header section 5. Further, communication holes 45 are formed inportions of the second flow diverging plate 41, the portions facing thesections 43 and 44, so as to establish communication between thesections 43 and 44 and the upper space 6 a of the refrigerant outletheader section 6.

The heat exchange tubes 14 of the third heat exchange tube group 16Acommunicate with the right-side section 43 of the refrigerant outletheader section 6, and the heat exchange tubes 14 of the fourth heatexchange tube group 16B communicate with the left-side section 44 of therefrigerant outlet header section 6.

Except for the above-described structural feature, the evaporator 40 isidentical with the evaporator 1 of the first embodiment.

Third Embodiment

The present embodiment is shown in FIGS. 4 a and 4 b, which show theentire structure of an evaporator.

In the case of the evaporator 50 shown in FIGS. 4 a and 4 b, theinteriors of the sections 29 and 31 of the second intermediate headersection 11 of the second header tank 3 are divided into two spaces 29 aand 29 b and two spaces 31 a and 31 b, respectively, in the verticaldirection (the longitudinal direction of the heat exchange tubes 14) bythird horizontal flow diverging plates 51 and 52 (second intermediateheader section flow diverging members). Communication holes 53 areformed in the third flow diverging plates 51 and 52 so as to establishcommunication between the upper space 29 a and the lower space 29 b ofthe section 29 and between the upper space 31 a and the lower space 31 bof the section 31. The communication portion 32 at the right endestablishes communication between the right-side section 27 of the firstintermediate header section 9 and the lower space 29 b of the right-sidesection 29 of the second intermediate header section 11. Further, thecommunication portion 33 at the left end establishes communicationbetween the left-side section 28 of the first intermediate headersection 9 and the lower space 31 b of the left-side section 31 of thesecond intermediate header section 11.

The heat exchange tubes 14 of the third heat exchange tube group 16Acommunicate with the upper space 29 a of the right-side section 29 ofthe second intermediate header section 11, and the heat exchange tubes14 of the fourth heat exchange tube group 16B communicate with the upperspace 31 a of the left-side section 31 of the second intermediate headersection 11.

Except for the above-described structural feature, the evaporator 50 isidentical with the evaporator 1 of the first embodiment.

Fourth Embodiment

The present embodiment is shown in FIGS. 5 a and 5 b, which show theentire structure of an evaporator.

In the case of the evaporator 60 shown in FIGS. 5 a and 5 b, thecommunication portions 32 and 33 are not provided on the opposite endsof the second header tank 3. Instead, at predetermined intervals in theleft-right directions, a plurality of refrigerant passage holes 61 areformed in the partition wall 13, which divides the interior of thesecond header tank 3 into front and rear spaces, to thereby form thefirst intermediate header section 9 and the second intermediate headersection 11. Accordingly, the refrigerant having flowed into the sections27 and 28 of the first intermediate header section 9 flows into thesections 29 and 31 of the second intermediate header section 11 via therefrigerant passage holes 61.

Except for the above-described structural feature, the evaporator 60 isidentical with the evaporator 1 of the first embodiment.

FIG. 6 shows a modification of the refrigerant inlet header section 5 ofthe first header tank 2 used in the evaporators 1, 40, 50, and 60 of thefirst through fourth embodiments.

As shown in FIG. 6, at predetermined intervals in the left-rightdirection, a plurality of flow diverging means, each of which isconstituted by a flow diverging opening 24 assuming the form of athrough hole, are provided in each of portions of the first flowdiverging plate 19, the portions facing the sections 22 and 23, so as tocause the refrigerant having flowed into the upper space 5 a of therefrigerant inlet header section 5 to diverge into the sections 22 and23. In the present embodiment, the number of the flow diverging openings24 provided for the right-side section 22 close to the refrigerant inlet7 is smaller than the number of the flow diverging openings 24 providedfor the left-side section 23 located away from the refrigerant inlet 7.Thus, the amounts of refrigerant flowing into the right-side section 22and the left-side section 23 are rendered uniform. In the case where thenumber of the flow diverging openings 24 provided for the right-sidesection 22 is equal to the number of the flow diverging openings 24provided for the left-side section 23, the refrigerant having flowedfrom the refrigerant inlet 7 into the upper space 5 a of the refrigerantinlet header section 5 more easily flows into the flow divergingopenings in a region close to the refrigerant inlet 7, so that therefrigerant more easily flows into the right-side section 22.

1. A heat exchanger comprising first and second header tanks disposedapart from each other; and a plurality of heat exchange tubes which aredisposed between the header tanks and whose opposite end portions areconnected to the corresponding header tanks, wherein the first headertank includes a refrigerant inlet header section and a refrigerantoutlet header section juxtaposed in an air flow direction, the secondheader tank includes a first intermediate header section and a secondintermediate header section juxtaposed in the air flow direction, andthe heat exchange tubes establish communication between the refrigerantinlet header section and the first intermediate header section andcommunication between the refrigerant outlet header section and thesecond intermediate header section, wherein a portion of the interior ofthe refrigerant inlet header section, the portion communicating with theheat exchange tubes, is divided into a plurality of sections in alongitudinal direction of the header tanks; flow diverging means isprovided in the refrigerant inlet header section so as to causerefrigerant having flowed into the refrigerant inlet header section todiverge into the sections; each of the interiors of the firstintermediate header section and the second intermediate header sectionis divided into sections in the longitudinal direction of the headertanks, the number of the sections being equal to the number of thesections of the refrigerant inlet header section; the heat exchangetubes communicating with the sections of the refrigerant inlet headersection communicate with the corresponding sections of the firstintermediate header section; and the sections of the first intermediateheader section communicate with the corresponding sections of the secondintermediate header section.
 2. A heat exchanger according to claim 1,wherein the interior of the refrigerant inlet header section is dividedinto two spaces in the longitudinal direction of the heat exchange tubesby an inlet header section flow diverging member; a first space of therefrigerant inlet header section located on a side toward the heatexchange tubes serves as the portion communicating with the heatexchange tubes; the first space is divided into a plurality of sectionsin the longitudinal direction of the header tanks by an inlet headersection partition member; refrigerant flows into a second space of therefrigerant inlet header section located on a side opposite the heatexchange tubes; and flow diverging means composed of a flow divergingopening is provided in each of portions of the inlet header section flowdiverging member corresponding to the sections of the first space so asto cause refrigerant having flowed into the second space of therefrigerant inlet header section to diverge into the correspondingspaces.
 3. A heat exchanger according to claim 1, wherein each of thesections of the second intermediate header section of the second headertank is divided into two spaces in the longitudinal direction of theheat exchange tubes by a second intermediate header section flowdiverging member, and communication is established between the twospaces of each section.
 4. A heat exchanger according to claim 1,wherein the interior of the refrigerant outlet header section of thefirst header tank is divided into two spaces in the longitudinaldirection of the heat exchange tubes by an outlet header section flowdiverging member; a space of the refrigerant outlet header sectionlocated on a side toward the heat exchange tubes serves a portioncommunicating with the heat exchange tubes; the space located on theside toward the heat exchange tubes is divided into a plurality ofsections in the longitudinal direction of the header tanks by an outletheader section partition member, the number of sections being equal tothe number of sections of the refrigerant inlet header section; and thesections of the space located on the side toward the heat exchange tubescommunicate with a space of the refrigerant outlet header sectionlocated on a side opposite the heat exchange tubes.
 5. A heat exchangeraccording to claim 1, wherein each of the number of the sections of therefrigerant inlet header section of the first header tank, the number ofthe sections of the first intermediate header section of the secondheader tank, and the number of the sections of the second intermediateheader section of the second header tank is two; the sections of thefirst intermediate header section and the second intermediate headersection located on one side with respect to the longitudinal directionof the header tanks communicate with each other via a communicationportion provided at one end of the second header tank; and the sectionsof the first intermediate header section and the second intermediateheader section located on the other side with respect to thelongitudinal direction of the header tanks communicate with each othervia a communication portion provided at the other end of the secondheader tank.
 6. A heat exchanger according to claim 1, wherein theinterior of the second header tank is divided into two spaces in the airflow direction by a partition member so that the first intermediateheader section and the second intermediate header section are formed;and refrigerant passage holes are formed in the partition member so asto establish communication between the first intermediate header sectionand the second intermediate header section.